Yarn tension means for warp knitting machines



Nov. 26, 1968 R. H. HAEHNEL 3,412,583

YARN TENSION MEANS FOR WARP KNITTING MACHINES Filed Jan. 27, 1967 222/ ELE J T 1 50 7 3/ 54 .54 a; as a7,a0 39 United States Patent ice 3,412,583 YARN TENSION MEANS FOR WARP KNITTING MACHINES Rudolf H. Haehnel, West Lawn, Pa., assignor to Textile Machine Works, Wyomissing, Pa., a corporation of Pennsylvania Filed Jan. 27, 1967, Ser. No. 612,240 Claims. (Cl. 66-146) ABSTRACT OF THE DISCLOSURE The disclosure herein concerns warp yarn tension bars for warp knitting machines, such as tricot machines, such tension bars comprising a rail over which the warp yarns are drawn in their paths from the warp supply to the knitting instrumentalities of the machine, the rail being supported by a plurality of spaced cantilever spring strips, and is directed particularly to the provision of adjustable snubbers for said strips whereby the characteristics thereof may be varied as required by varying conditions of the machine operation.

Background of the invention The invention concerns warp knitting machines such as tricot machines and is directed particularly to means for modifying the operation of the devices which control the tension in the yarns being converted into fabrics.

Warp knitting machines comprise knitting instrumentalities including needles and other elements to which yarns are fed by yarn guides, one for each yarn. In each knitting cycle the yarn guides are given a motion to in effect Wrap their respective yarns around individual needles, the needles and other instrumentalities thereafter being operated to convert the yarn into knitted stitches. The yarns are delivered to the guides in the form of sheets from two or more beams. Due to the motion of the yarn guides and of the needles and other knitting instrumentalities a fluctuating demand for the yarn is created in each knitting cycle. This, taken in connection with the fact that, from a practical standpoint, the yarn beams must be rotated at a substantially uniform speed throughout each knitting cycle, has resulted in the employment of a yarn tension device for each sheet of yarns and over which they pass on their Way from their beams to the warp guides. Conventionally such tension device comprises a rail carried by means so constructed as to yield under spring tension upon the pull of the yarns when the demand for the yarns increases and to relax and still apply tension to the sheet of yarns when the demand eases.

Such known types of tension means are illustrated for example in patents to Welch 1,898,106, issued Feb. 21,

1933; Bolden et al. 2,308,430, issued Jan. 12, 1943;

Schoenster 2,637,184, issued May 5, 1953 and Trumpio 2,844,950, issued July 29, 1958. Referring for example to the Bolden et al. Patent 2,308,430 which discloses a construction substantially that to which the instant invention is applied, the tension device comprises a rail over which the yarns pass and cantilever spring means for supporting the rail from a fixed portion of the machine. The cantilever spring means may, as in the case of the instant invention, be separated strips of spring sheet metal.

Summary of the invention Briefly summarized the invention resides in a warp knitting machine, such as a tricot machine, having a tension bar arrangement similar to that disclosed by the above referred embodiment of the Bolden et al. patent. The invention is particularly directed to and has for its 3,412,583 Patented Nov. 26, 1968 principal object the provision of means for adjustably modifying the characteristics of each or of a purality of such sheet metal spring members or strips, such means in the preferred embodiment of the invention comprising a bracket supported from a frame member of the machine to overlie an associated spring member, such bracket carrying a snubber element for contact with the spring metal strip intermediate the ends of the latter. The snubber element is suitably mounted for vertical adjustment in its bracket. Snubbers of the present invention serve to prevent excessive upward movement of the guide rail as well as serving to dampen the vibratory frequency or fluttering of the rails. Further-more by their adjustable feature they may be set to preload the metal spring strips to modify the spring constant, i.e., the force required for a given deflection thereof.

Brief description of the drawings FIG. 1 is a cross-sectional view taken transversely through a portion of a tricot knitting machine and of the yarn tensioning mechanism therefor incorporating the invention, dot-and-dash distance breaks being used to indicate omission of intervening mechanism;

FIG. 2 is a plan view of the upper yarn tensioning mechanism illustrated in FIG. 1; and

FIG. 3 is an elevational view on an enlarged scale of a portion of the yarn tensioning mechanism according to the invention.

Description of preferred embodiment Referring to the drawings and particularly to FIGS. 1 and 2 there is shown certain known portions of a warp knitting machine, such as a tricot machine, such parts including knitting elements indicated diagrammatically at 10 and which would include needles, sinkers and the like as well as front and rear rows of yarn guides 12 and 14 for yarns indicated at 16. The knitting elements are operated at high speed, say up to one thousand cycles per minute, in the usual manner to form the yarn, lapped around the needles by the guides 12 and 14, into loops of the fabric. The yarns 16 for the front and rear groups of yarn guides follow separate upper and lower paths respectively and are withdrawn from their respective supply beams portions of which are shown at 18 and 20. The yarns 16 in the upper path pass through a conventional comb separator 21 and over a guide'22 suitably comprising a U-shaped chrome plated steel member clipped to a marginal portion of reduced thickness of the vertical flange 24 of an angle member 26 supported from the machine frame members 28 as by brackets 29. From guide 22 the sheet of yarns is directed over a guide rail 30 of a tension device 31, the guide rail suitably comprising a U-shaped chrome plated steel member extending across the sheet of yarns. From the guide rail the yarns pass to the front group of yarn guides 12. The yarns 16 in the lower path are similarly directed through a separator comb over a fixed guide 22 and a guide rail 30 of a tension device 31, supported from the machine frame as previously described, to the rear group of guides 14.

During the knitting operation of the machine the yarn guides 12 and 14 are moved through the needle row, then shifted transversely of the needle row and thence back to their original position to lap or loop the yards around the needles and the needles are simultaneously operated to form the yarns into loops of the fabric. This movement of the yarn guides and of the needles and other knitting instrumentalities results in a variation in the demand for the yarns thereby tending to cause a periodic increase and decrease in the tension in the yarns between the yarn guides and guide rails 30. In order to maintain a relatively constant but light tension in the yarns at this time, the guide rails are mounted to follow rapidly varying demand for the yarns and for this purpose are each carried by a series of spaced thin gauge steel spring strips 38 forming cantilever supports for its associated guide rail, the guide rails and spring strips together forming the tension devices 31. Suitably the guide rails are clipped over the ends of straps 37 each of which is secured to an associated spring strip 38 as by rivets 39. The strips of each tension device are conventionally mounted, as illustrated particularly in FIG. 3. In those cases where a spring strip is opposite to a bracket 29 the inner end of the spring strip is confined between a flange of such bracket and the lower flange of angle bar 26. However where the spring strips are located intermediate the brackets 29 their inner ends are confined between a plate 42 and flange 44 of angle bar 26. In both cases the parts are held in assembled relationship by bolts or studs 48.

In accordance with the instant invention and in order to permit the modification of the spring characteristics of spring strips 38 as well as to prevent excessive upper movement of the guide rails 30 and to dampen the vibratory frequency or fluttering of the rails, all or spaced ones of the metal strips of, suitably, both tension devices are provided with mechanism indicated generally at 50 and illustrated in more detail in FIG. 3. Each mechanism 50 comprises a rigid support member or bar 52 having an inner end secured to the lower flange 44 of angle member 26 as by one of the bolts 48 previously reterred to. The outer free end of member 52 overlies its associated spring strip 38 at an intermediate point of the length thereof and includes a threaded opening receiving a stud 54. A cap piece 56 formed of nylon or other suitable material is carried by the lower end of the stud. The position of cap piece 56 with respect to its associated spring strip is adjusted by rotation of stud 54, the upper end of the stud being provided with a kerf 57 for the reception of a screw driver or the like, and the stud and hence the cap piece is maintained in any such adjusted position by a lock nut 58.

As will be understood the mechanisms 50 may be associated with all or with only spaced ones of the spring strips. Also the amount of preloading of the strips, the preloading being determined by the extent to which the strips are depressed from their unstressed position by the studs 54, will depend upon the conditions encountered and may vary over the length of the guide rail and in some instances no preloading may be required. Ordinarily there is a substantial difierence in the tension of those yarns which form the central section of the fabric and those which form the sections adjacent the selvages. Under such circumstances the mechanisms 50 overlying the spring strips adjancent the central part of the guide rails may be adjusted to provide substantial preloading of their associated spring strips while the mechanisms adjacent the ends of the rails may be adjusted for only a light preloading or none at all. It will be appreciated that whether or not the mechanisms 50 perform a preloading function they continue to serve their damping or flutter controlling function. Due to the construction of the mechanisms 50 required adjustments may be made while the machine is in operation.

Having thus described the invention in rather complete detail it will be understood that these details need not be strictly adhered to and that various changes and modifications may be made all falling within the scope of the invention as defined by the following claims.

I claim:

1. In a yarn tensioning means for a textile fabricating machine including a yarn supply beam carrying a plurality of yarns thereon, means for converting said yarns into fabric, and a tension device in the paths of said yarns from the supply beam to said yarn converting means, said tension device comprising a rail over which said yarns are passed in a form of a sheet of yarns, a plurality of cantilever members comprising spring strips carrying said rail, and means supporting said spring strips, the improvement comprising; means supported independently of said cantilever members for contacting at least some of said spring strips at a point intermediate said support and said rail, and means to adjust the position of said contacting means relatively to said spring strips.

2. A tensioning means as defined in claim 1 wherein said spring strip contacting means comprises a support member overlying its associated spring strip and means carried by said support member at a point intermediate the length of said spring strip for adjustment toward and away from said spring strip.

3. A yarn tensioning means as defined in claim 2 wherein said means carried by said support member comprises a threaded member received in a threaded opening in said support member.

4. A yarn tensioning means as defined in claim 3 wherein said threaded member carries a cap piece for contact with said spring strip.

5. A yarn tensioning means as defined in claim 4 wherein there is a locking means cooperating with said threaded member for securing the latter in any adjusted position.

References Cited UNITED STATES PATENTS 277,449 5/1883 Brady 242-151 2,308,430 1/1943 Bolden et a1 66-146 XR 2,449,105 9/1948 Bradley et al. 66-146 2,637,184 5/1953 Schoenster 66-146 2,699,051 1/1955 Noe 66-146 XR 2,811,027 10/1957 Held 66-146 MERVIN STEIN, Primary Examiner. 

